Manufacture of return bends and similar structures



June 14, 1932. c. H. TRUE 1,863,033

MANUFAQTURE OF RETURN BENDS AND SIMILAR STRUCTURES Filed Nov. 22, 1928 1 N V EN TOR.

A TTORNEY.

Patented June 14, 1932 UNITED STATES PATENT OFFICE CHARLES H. TRUE, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE SUPERHEATER COM- IPANY, OF NEW YORK, N. Y.

MANUFACTURE OF RETURN BENDS AND SIMILAR STRUCTURES Application filed November 22, 1928. Serial No. 321,141.

This invention relates to the process of making elbows and similar structures, an has for its purpose the provision of a process by which such structures can be made quickly and cheaply without any danger of the inner cross-sectional areaof the structure becoming unduly restricted during manufacture.

The process is in generalone of beginning with a straight length of tubing and bending it through the necessary angle and entirely avoids the formation of restrictions in the interior such as have often resulted in the past when methods hitherto known have been employed.

The invention is illustrated in the drawing herewith in which Fig. 1 is a longitudinal section of a pipe length such as I employ in my process; Fig 2 is an end view of Fig. 1; Figs. 3 and 5 are views corresponding to Fig. 1 of the partly finished article at different stages of the process; Figs. 4 and 6 are end views of Figs. 3 and 5 respectively; Fig.

7 is a view corresponding to Fig. 1 at a still g later stage of the procedure; and Fig. 8 is an elevational view partly in central section of the finished product.

The pipe length 1 is of a larger diameter than the diameter desired in the finished product. The length of this piece of pipe is such as required by the finished product.

The first step in the process is to swage down the two ends of the length of pipe for a, suitable distance, as indicated at points 1-1 of Fig. 3. The diameter of these swaged down portions is approximately that of the finished article. It will be noted from an inspection of Figs. 3 and 4 that the axes of the swaged down portions 11 are alined with each other but are not alined with the axis of the portion 2, which retains the original diameter,

and that the walls of the portions 1-1 are tangent to the wall of the portion 2. 7 After the portions 1.'-1 have been swaged down as just described, the central poi'tlon 2 is flattened down to bring the portions 4-4,

which in the form of Fig. 4 protruded laterally be 0nd the end portions 1, so thatthey lie wit in such limits, and that no parts of the portions 4.4 extend laterall beyond the swaged down portions 1-1. After the piece has been given the form indicated in Figs.

(1 5 and 6, it is next bent into the form indicated in Fig. 7. This is done over the usual bending die which will prevent the portions 44: from bulging out. The part 5 of the wall will, during such bending, approach the part 6. In other words, the structure will during such bending partially collapse, but inasmuch as the portion 5 was at a greater distance from 6 than is desired in the final product, this partial collapse will result in an ultimate distance between these two parts equal to the diameter of the parts 1 1. The size of the pipe originally selected is chosen with a view to bring about this very result. If the pipe islarger than necessary, the distance between 5 and 6 would be larger than the diameter of the parts 11, while if the pipe were too small originally, the distance between 5 and 6 would become smaller than the diameter of the parts 11. In practice it is not diflicult to select exactly the right diameter to ive the desired form.

After the article has been given the shape of Fig. 7 provision must be made for pipe connections. By way of illustration there are shown in Fig. 8 end flanges screwed on the piece which has been provided with threads. Other forms of connections can of course be used.

It will be obvious that while for the purpose; of illustration a bend has been shown, the two branches of which are at right-angles to each other, the same process can be used for structures in which these two branches are at some other angle. They may, in fact, be anything between a straight .line and 180.

Moreover, my invention is not limited to the precise order of steps above disclosed. For instance, it is not necessary that the unswaged central portion 2 of the pipe length be flattened before bending or that the step of swaging precede that of bending.

I claim: p y

The process of making an, elbow comprising the steps of selecting a pipe length of a diameter larger by a suitableamount than the desired diameter of the finished product, swaging down the ends of the pipe to the diameter of the final product, ortions of the walls of the two swaged ends ing in alinement with each other and with a portion of the wall of the unswaged part of the pipe, flattening the unswaged part so no porgent to the swaged portions, and bendin the piece into final shape with the said aline portions of the wall on the inside of the curve of the elbow, whereby the free inner crosssectional area is nowhere smaller than at the swaged ends.

CHARLES H. TRUE.

tion extends beyond two'parallelplanes tani 

